1. Field of the Invention
This invention relates to an automatic braking system and, more particularly, to an automatic braking system for use with a rotary apparatus.
2. Description of the Prior Art
In the prior art, braking systems for rotary devices, such as turbine powered rotary devices, utilize one or more rods which press against a brake disk attached to the rear portion of the rotary device. The friction produced by the rod(s) pressing against the braking disk causes the disk and a rotating rotor to stop rotating. Movement of such rod(s) may be controlled by a valve member which also controls the flow of compressed air into the rotary device.
For example, consider the air motor described in U.S. Pat. No. 5,186,603. As described therein, the air motor generally includes a front housing, a rear housing which is fitted to a rear portion of the front housing, a rear cap coupled to the rear portion of the front housing, and a valve sleeve which is slidably fitted to an outer periphery of a small-diameter rear portion of the rear housing. A valve inside cylinder having a supply port for receiving compressed air is fitted into the valve sleeve. A rotor is installed in a rotor chamber formed by the inside rear portion of the front housing and a front portion of the rear housing. The rotor is coupled to one end of a rotary shaft to which the other end may be coupled to a grinding tool.
A brake disk is secured to the rear surface of a rear portion of the rotor. A brake rod(s) is linked with the valve outside sleeve so as to be movable therewith.
The valve sleeve may be moved in an axial direction by turning an external thread formed on an outer periphery of the front portion of the valve sleeve against an internal thread of the rear cap. When the valve sleeve is maximally withdrawn or moved in one direction, the rear housing is separated from the valve inside sleeve so as to open a fluid channel in the valve inside cylinder and enable compressed air to flow to the rotor, thus causing the rotor to rotate. On the other hand, when the valve sleeve is moved in the other direction so as to close the fluid channel, the flow of compressed air is stopped. Additionally, in this latter situation, the brake rod(s) is moved so as to be pressed against the brake disk, thereby exerting a frictional force upon the rotating rotor so as to cause the rotor to stop rotating.
Thus, in such air motors, the valve sleeve or member, which is utilized for controlling the flow of compressed air to the rotor, is mechanically linked to a brake rod(s) so as to control the movement thereof and is located at the rear of the air motor. As is to be appreciated, such arrangement limits the placement of such valve member in the rotary device.